Air venting means for photographic film unit

ABSTRACT

A SELF-DEVELOPING PHOTOGRAPHIC FILM UNIT ADAPTED TO BE PROCESSED BY BEING MOVED BETWEEN TWO PRESSURE-APPLYING ROLLERS. A TRANSPARENT SHEET IS HELD IN FACE-TO-FACE CONTACT WITH THE PHOTOSENSITIVE SHEET WITH AN LIQUID PROCESSING COMPOSITION BEING FED BETWEEN THE SHEETS AND ARRANGED SO THAT EXCESS PROCESSING LIQUID IS COLLECTED AFTER THE PHOTOSENSITIVE SHEET HAS BEEN COVERED AND ANY AIR TRAPPED WITH THE PROCESSING LIQUID IS ALLOWED TO ESCAPE. THE ESCAPE MEANS PROVIDED IS AN UNSEALED PORTION OF A FOLD IN THE BINDING MATERIAL THAT HOLDS THE SHEETS TOGETHER.

Oct. 30, 1973 R. J. CHEN Re. 27,

AIR VENTING MEANS FOR PHOTOGRAPHIC FILM UNIT Original Filed Aug. 19.1969 INVENTOR. 2 RICHARD CHEN W M m ew ma a? W A TTURIVEYS United StatesPatent Office Re. 27,795 Reissued Oct. 30, 1973 27,795 AIR VENTING MEANSFOR PHOTOGRAPHIC FILM UNIT Richard J. Chen, Winchester, Mass., assignorto Polaroid Corporation, Cambridge, Mass.

Original No. 3,589,904, dated June 29, 1971, Ser. No. 851,290, Aug. 19,1969. Application for reissue Nov. 1, 1971, Ser. No. 194,72

1 Int. Cl. G03]: 17/50 U.S. CI. 95-13 9 Claims Matter enclosed in heavybrackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION (A) Field of theinvention This invention relates to self-developing photosensitive filmunits and, more particularly, to such a unit which has a compartment atthe trailing edge thereof for collecting excess processing liquid withmeans also provided for allowing trapped air to escape.

Film units of the type with which the present invention is concernedcomprise a photosensitive sheet placed in face-to-face relationship witha transparent sheet. After the photosensitive sheet is exposed throughthe transparent sheet, a processing liquid composition is spread betweenthe two sheets so that the scene can be recorded by the diffusiontransfer process more completely de scribed in U.S. Pat. No. 3,415,644,assigned to the same assignee as the present invention. The spreading ofthe processing composition is brought about by moving the film unitprogressively through pressure-applying members, such as rollers,thereby driving a quantity of processing liquid across a photosensitivesheet in front of the rollers. Typically the processing liquid iscontained in one or more pods disposed near the leading edges of thephotosensitive and transparent sheets. The pods are ruptured by pressuredeveloped by the rollers during the initial movement of the unit. Thiscauses a discharge of processing liquid into an open space between thetwo sheets. It should be noted that the pods are generally formed by awrapped single sheet of material that is sealed at its sides butweakened at its seal in the direction of the sheets. Therefore, when therollers apply the pressure in the pod, the weakened seal ruptures andthe processing liquid escapes in the proper direction.

One of the basic problems associated with spreading the processingliquid across the photosensitive sheet is to insure an even spreading ofthe liquid over the exposed area. Due to slight variations intemperature and viscosity of the processing liquid, a slight excess ofthe liquid is provided in the pods over that required to completelycover the exposed photosensitive sheet. As set forth in U.S. Pat. No.3,415,644, the processing liquid has a certain toxicity whichnecessitates that it not be allowed to escape from the unit. Therefore,the excess processing liquid must be contained within the unit in such aman net that it does not casually escape, while, at the same time,allowing trapped air present between the sheets to escape. It is obviousthat the amount of excess liquid cannot be predicted with exactprecision, and therefore a collection area must be provided which has acapacity to accept a predetermined maximum amount. At the same time, thechamber cannot be extremely oversized in that some chamber support mustbe provided, and this necessarily increases the cost of the unit. Statedanother way, the chamber provided for the excess liquid in the presentinvention is established extending the transparent sheet some distancebeyond the photosensitive sheet. In this manner the size of thecompartment for excess liquid is determined by the amount of extensionof the transparent sheet past the photosensitive sheet, which of courseis shorter.

The compartment above described is maintained at a given volume by theexpedient of embossings extending from the transparent sheet into thearea where the photosensitive sheet would be disposed, but for its beingshortened. One such type of embossings is described in U.S. Pat.3,619,193, [application Ser. No. 787,749] filed Dec. 30, 1968, andassigned to the same assignee as the present invention. However, theposition of the embossings blocks air escape and some means must beprovided when using these embossings for the escape of air to make thefilm unit completely foolproof. It should be made clear that the needfor the embossings is because some means for maintaining the desiredvolume of the compartment is necessary. Otherwise the pressure of therollers would drive the walls of the compartment together when passingover the compartment as the unit exits therefrom. Accordingly, theembossings keep the rollers spaced when passing over the compartment.

(B) Prior art Pat. No. 3,619,749 [Ser. No. 787,749] provides thenecessary structure to prevent chamber collapse, but could conceivablyprevent adequate space for trapped air to escape were air to be trappednear the center of the compartment unless air-escape means were providedin that area. Prior art film units of the type shown in Pat. No.3,619,193 [Ser. No. 787,749] also provide means for air-escape bypuncturing sides of the fluid trap compartments. However, the provisionof air vents requires a separate step in the manufacturing process whichnecessarily increases the cost of the units and, consequently, isundesirable. In addition, air trapped in the center of the compartment,that is, between the embossings, cannot reach the air-escape means.

OBJECTS OF THE INVENTION Accordingly, it is an object of the presentinvention to provide an improved self-developing film unit which has achamber for trapping excess processing liquid and which also provides aninexpensive means for allowing the escape of trapped air, irrespectiveof where in the compartment the air is trapped.

It is another object of the present invention to provide an improvedself-developing film unit which has a minimum number of parts and whichguarantees that a predetermined volume of the compartment is maintainedduring processing of the unit between spread rollers.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises an article of manufacture possessingthe features, properties, and relation of elements which will beexemplified in the article hereinafter described and the scope of theapplication of which will be indicated in the claims.

SUMMARY OF THE INVENTION Briefly, I accomplish the foregoing objects bythe provision of embossed areas in one portion of the film unit and byleaving selected areas of a unit binder unsealed to allow the escape oftrapped air. More specifically, a photosensitive sheet is placed inface-to-face relation with a second transparent sheet which is longerthan the photosensitive sheet. In certain areas of the extra length, thetransparent sheet is embossed to a depth approximating the thickness ofthe photosensitive sheet, thereby forming a compartment. Paper bindingis wrapped over the trailing end of both sheets and sealed near the endof the photosensitive sheet and across the top of the transparent sheet.This forms a compartment near the trailing edge section of both sheets.The embossing in the transparent sheet is characterized by a pair ofoffset depressions near both trailing edge corners. This insures thatthe roller cannot compress the compartment in any area, but becauseneither embossed area stretches the full width of the compartment, aserpentine path always exists for the escape of trapped air to theextremities of the trailing edge sections. The paper binder that formsthe outer wall of a portion of the container is folded over near thecorners and partially sealed. The portion that is not sealed leaves avery thin air-escape route from the compartment near either rear corner.The area left open is small enough to prevent the escape of any liquidbut is large enough to allow the escape of air. Therefore, the presentinvention teaches a novel method of maintaining a compartment in thefilm unit of the type described with a predetermined volume whileinexpensively allowing the passage of air that is trapped in thecompartment to escape.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of thecomposite film unit of the subject invention;

FIG. 2 is an exploded, perspective view of the pair of the sheets andbinding means of the present invention;

FIG. 3 is a partial plan view of a portion of the film unit of FIG. 1;and

FIG. 4 is a sectional view taken along lines 44 of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, a film unitgenerally designated by numeral is shown. Film unit 10 comprises aleading edge section 12 composed of pods 14a, 14b, and 14c, centerportion 16, and trailing edge section 18. Leading edge section 12 isgenerally composed of a single sheet folded over as illustrated at 20,and a film sealed along edges 22 and 24. In area 26, which isimmediately adjacent center section 16, a seal is provided but is of aweakened type. Leading edge 28 is of course formed of the folded-overmaterial and is sealed, forming an area tightly sealed on three sideswith the fourth side closed by the weakened seal. Therefore, as pressureis placed on any of the pods 14a, b, or c, which ar filled with aprocessing composition, hydraulic pressure will build up in the podsuntil a rupture thereof takes place. Designedly, this rupture takesplace only in area 26.

Referring to FIG. 2, the remainder of the film unit 10 is shown.Transparent sheet 30 and photosensitive sheet 32 generally comprisecenter section 16. These sheets are placed in face-to-face dispositionwith their leading edges 34 and 36, respectively, being substantiallycoextensive. Trailing edges 38 and 40, respectively, however, are notcoextensive for reasons hereinafter explained. Binding means 42 issubstantially a sheet of paper cut to the appropriate dimensions andfolded along the dotted lines shown in FIG. 2 so as to wrap aroundsheets 30 and 32 to form the remainder of film unit 10. As hereindescribed,

therefore, trailing edge section 18 comprises the portion of transparentsheet 30 that extends beyond photosensitive sheet 32 and the portion ofthe binding means 42 that wraps around the extended trailing edge 38 andis fastened near the end of trailing edge 40 of sheet 32. Therefore,when appropriately assembled, as best seen in FIGS. 3 and 4, acompartment 44, the thickness of sheet 32, is formed.

Referring to FIG. 3, the underside of one of the corncrs of the filmunit shown in FIG. 1 is illustrated. Binding means 42 is wrapped aroundthe sheets placed in faceto-face relationship so as to form the fold 46.Fold 46 is sealed in area 48 and in area 50 so as to allow a path forair to escape from compartment 44 through the unsealed area 52 of fold46. The corner illustrated in FIG. 3 is duplicated in mirror image onthe corresponding opposite corner of trailing edge section 18.

Embossings 54 and 56 are, in fact, depressed portions of transparentsheet 30 extending downward therefrom a distance substantially the samedistance as the thickness of sheet 32. Embossing 54 extends fromtrailing edge 40 of sheet 32 parallel to the longitudinal axis ofcompartment 44 to the rear and on a plane normal thereto, as best seenin FIG. 3. Similarly, embossing 56 is parallel but offset with respectto embossing 54 and extends forwardly from trailing edge 38 of sheet 30.The arrows in FIG. 3 illustrate the serpentine path for air flow betweenthe offset embossed areas with the exit for the air being in area 52.Accordingly, the collective volume of the space between sheets 30 and 32plus compartment 44 exceeds the volume of the total processing liquid.

Referring to FIG. 4, binding means 42 is shown as being sealed to sheet30 at 58 and is sealed to sheet 32 at 60. Accordingly, compartment 44 ismaintained with practically its complete volume intact even when filmunit 10 is drawn between pressure rollers and the lower roller traversesthe area beyond photosensitive sheet 32. A minimum-thickness package isthereby provided with adequate support in the area where the excessprocessing liquid is collected, at the same time allowing an inexpensiveair exit to be provided. Area 52, which is the area for air exit, alwayshas a portion thereof in an open condition as a roller moves relative tothe trailing edge section. This effect is made possible by the tapers ofthe fold from the inner margin 62 of the binding means 42 toward thetrailing edge of the film unit defined by line 64. Therefore, noseparate machining operation to form an air vent is required as thebinding means must be provided to hold the film unit intact. This uniqueair vent means is always left in an open condition for the venting ofair regardless of the position of the compression rollers at a givenmoment due to the fact that the opening is defined by a flap disposed atsome angle relative to the longitudinal axis of the film unit. This ismade clear by the relative angular position of areas 50, 52, and 64.

In operation, photosensitive sheet 32 is exposed through transparentsheet 30. This is done by a typical shutter mechanism in a camera of thetype described in Ser. No. 655,850, now abandoned, assigned to the sameassignee as the present invention. When this occurs, as set forth in theaforementioned application, the film unit 10 is driven betweencompression rollers starting with leading edge 28. As the rollersprogress into pods 14, 14b, and 14, a pressure build-up occurs thereinand a controlled rupture takes place in area 26. This results in aparting of the folded-over sheet 22 resulting in the injection of aprocessing composition between sheets 30 and 32. It is clear that sheets30 and 32 are peripherally sealed by binding means 42 except on the sideadjacent area 26. This results in the processing composition beingspread between sheets 30 and 32 as the rollers progress toward thetrailing edge section. As previously described, an excess of developingor processing material is needed from that capable of completelycovering the exposed area of sheet 30. The substance of the presentinvention is involved in handling this excess of processing material andair trapped with it.

Referring to FIG. 4, it will be assumed that the rollers are disposed oneither side of the trailing edge section 18 over sealed areas 58 and 60.Presumably, some air has been driven in front of the rollers, betweenthe sheets and is now disposed in compartment 44. As the excess ofprocessing liquid enters compartment 44, it is possible under somecircumstances that the amount of air trapped there be of sufficientquantity to leave insufi'icient volume for excess processing liquid.Therefore, this air would be compressed and possibly cause a refeedingof the excess material between sheets 30 and 32 but for some air-escapeprovision.

It should also be noted that it is impossible to predict in which areaof trailing edge section 18 air will be trapped, and it must be assumed,for purposes of reliability, that air is trapped in all areas ofcompartment 44 across the width thereof. By the same token, embossings54 and 56 prevent compartment 44 from collapsing under the pressure ofthe opposed rollers as this compartment is filled initially with air andthen with the processing liquid.

Referring to FIG. 3, when rollers progress along film unit so that theyare on either side of the trailing edge section 18, the trapped air willfollow a route denoted by the arrows and will exit in area 52. This ofcourse occurs on either side of trailing edge section 18 as previouslyexplained. Therefore, the air is not compressed and there is noresistance to the flow of excess processing liquid into compartment 44.Compartment 44 is designed to be of sufiicient size to accommodate theamount of excess liquid available under even the most adversecircumstances, this being due to any variance of viscosity due totemperature and/or pressure extremes. Therefore, the objects of theinvention have been realized in that film unit 10 can functionautomatically in the environment shown in Ser. No. 655,850, nowabandoned, while still maintaining a repository for the excessprocessing material, leaving no chance of its spurious escape from thefilm unit. After a short period of time, the excess liquid contained incompartment 44 will dry and will no longer present any type of problemto an operator because of its toxicity. This is especially true due tothe opening provided in the area 52 which allows air flow intocompartment 44 to accelerate the drying.

Since certain changes may be made in the above article without departingfrom the scope of the invention herein involved, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

[1. A photographic film unit of the type that is adapted to be processedby being moved, leading edge foremost, relative to and between at leasttwo pressure-applying members to distribute a liquid processingcomposition within said film unit toward a trailing edge thereof, saidfilm unit comprising:

a photosensitive sheet having a trailing edge section;

a second sheet having a trailing edge section; and binding means forholding said sheets in face-to-face relation with said trailing edgesection of one of said sheets extending beyond the trailing edge sectionof another of said sheets, thereby forming a compartment adjacent thetrailing edge section of the extending sheet for collecting excessliquid processing composition driven past the portions of the sheets infaceto-face relation;

said second sheet being embossed to form a plurality of offsetdepressions extending from said second sheet in a plane normal thereto adistance substantially the same as the thickness of said photosensitivesheet to maintain the integrity of said compartment as the sheets aredrawn between the pressure-applying members, said compartment having atleast one outlet therefrom formed by spaces between portions of saidbinding means] [2. A photographic film unit according to claim 1 whereinsaid spaces are formed by overlapped portions of said binding means thatare unsealed] [3. A photographic film unit according to claim 1 whereinsaid second sheet has a pair of offset embossed portions on each side ofsaid trailing end sections, thereby providing a path for trapped air insaid compartment to escape toward said outlets from the center portionof said compartment] [4. A photographic film unit according to claim 1wherein said binding means is folded over at each corner of saidtrailing edge sections and partially sealed so that space is providedfor the escape of air at a pressure above atmospheric but providinginsufficient space for escape of the liquid processing composition] [5.A photographic film unit according to claim 1 wherein said compartmentand the space between said transparent and photosensitive sheets has acollective volume in excess of the volume of processing liquid] [6. Aphotographic film unit according to claim 2 wherein said overlappedportions form openings defined by flaps disposed at some angle withrespect to the longitudinal axis of the film unit] [7. A photographicfilm unit according to claim 3 wherein said pair of embossed portionsincludes at least two depressions extending from said transparent sheetparallel to the longitudinal axis of said compartment, one of saiddepressions extending rearwardly from a trailing edge of saidphotosensitive sheet a distance less than the longitudinal length ofsaid compartment, a second of said depressions extending forwardly froma trailing edge of said transparent sheet a distance less than thelongitudinal length of said compartment] [8. A photographic film unitaccording to claim 7 Wherein the outermost depression extends from thetrailing edge of said transparent sheet] [9. A photographic film unitaccording to claim 7 wherein the innermost depression extends from thetrailing edge of said transparent sheet] [10. A photographic film unitaccording to claim 7 wherein a path for air escape from said compartmentto the exterior of said film unit is provided at all times, regardlessof the momentary position of the pressure-applying members relative tosaid film unit due to the offset position of said depressions and theangular disposition of said flaps] 11. In a photographic film unit ofthe type adapted to be processed by a liquid processing compositiondistributed within said film unit toward the trailing edge thereof byand in response to movement of said film unit, leading end foremost,relative to and between a pair of pressureapplying members, said filmunit including a photosensitive sheet having a trailing end section anda second sheet having a trailing end section, the improvementcomprising:

a binding sheet secured around and to margins of said photosensitive andsecond sheets for holding the latter in face-to-face relation with saidtrailing end section of one of said sheets extending beyond the trailingedge of the other of said sheets in facing relation to a trailing endportion of said binding sheet and cooperating therewith to form achamber f collecting and retaining excess liquid processing compositiondistributed beyond said trailing edge of said other sheet;

said extended trailing end section of said one sheet including aplurality of portions embossed normally to the plane of said one sheettoward the other of said sheets and said portion of said binding sheetto form a plurality of depressions and corresponding raised portionshaving, respectively, depths and heights at least equal to the thicknessof said other sheet to maintain the spacing betweeen said extendedtrailing end section and said portion of said binding sheet and theintegrity of said chamber as said extended end section and said portionof said binding sheet are moved between a pair of pressure-applyingmembers, said chamber havin at least one ut et therefrom formed byspaces between portions of said binding sheet to permit the escape ofair from said chamber.

12. A photographic film unit according to claim 11 wherein said secondsheet is said one sheet.

13. A photographic film unit according to claim 11 wherein said embossedportions include two pairs of closely spaced depressions, each of saidpairs being located adjacent a lateral edge of said extended trailingend section, said depressions of each pair extending in sideby-siderelation longitudinally of said film unit and overlapping one another toprovide a tortuous path for the escape of air laterally toward outletsin the lateral extremities of said chamber.

14. A photographic film unit according to claim I] wherein said extendedend section is formed with two pairs of embossed portions each locatednear a lateral edge of said extended end section and including a firstdepression extending from the trailing edge of said one sheet towardsaid trailing edge of said other sheet a distance approximately half thedistance between said trailing edges and the longitudinal dimension ofsaid chamber and a second depression extending from adjacent saidtrailing edge of said other sheet toward said trailing edge of said onesheet a distance of approximately half the distance between saidtrailing edges and said longitudinal dimension of said chamber.

15. A photographic film unit according to claim 14 wherein saiddepressions are of approximately the same width and the depressions ofeach pair are spaced from one another by approximately said width ofsaid depresstons.

16. A photographic film unit according to claim 14 wherein thedepression of each of said pairs closest the lateral edge of said onesheet extends from said trailing edge thereof toward the said trailingend thereof.

17. A photographic film unit according to claim 14 wherein thedepression of each of said pairs closest the lateral edge of said onesheet extends from adjacent said trailing edge of said other sheettoward said trailing edge of said one sheet.

18. A photographic film unit according to claim I] wherein said portionsof said binding sheet are sealed to one another in overlapped relationadjacent the corners of said extended end section of said one sheetexcept for sections of said overlapped portions left unsealed to oneanother to form said spaces.

19. A photographic film unit according to claim 18 wherein said bindingsheet is folded over at each corner of said extended trailing endsection and partially sealed to provide space for the escape of air at apressure above ambient and providing insufficient space for the escapeof liquid processing composition.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 3,615,540 10/1971 Land at al. 96-76 C 3,619,19311/1971 Knight 9676 R 3,615,436 10/1971 Campbell 9676 X 3,652,281 3/1972Bachelder et a1. 96-76 C 3,607,285 9/1971 Chen 9676 C 2,627,460 2/1953Land 96-76 X RICHARD L. MOSES, Primary Examiner US. Cl. X.R. 96-76 C

